Papers by Author: R.A. Vandermeer

Abstract: New 3D X-ray diffraction microscopy (3DXRD) experiments on recrystallizing bulk grains that nucleated and grew in a 92% cold deformed pure copper during in situ annealing at both 150° C and 160° C are described. Nucleation times, growth velocities and apparent activation energies were determined for each grain. A wide range of apparent activation energies was observed but the average of 123 kJ/mol agreed well with earlier recrystallization experiments on a similar purity copper. It was clear that each recrystallized grain had its own individual characteristics; the grains do not all behave alike as various models would suppose.

Abstract: In this work, it is shown that the contiquity ratio, Crr, defined as the fraction of the total grain boundary area of recrystallized grains shared by other recrystallized grains, is a useful experimental parameter for describing the clustering of recrystallization nuclei in partially recrystallized microstructures. Two experimental examples are presented where anisotropic impingement behavior, i.e. non random recrystallized grain distributions, is thought to be important. In the experimental examples, the deviation of Crr from Crr = Vv which is a characteristic of a random distribution, is clearly shown. The results justify the need for these cases to be modelled, as had been done, by impingement patterns other than the simple random nucleation behavior so often postulated without proof in recrystallization kinetics studies.